The properties of organic–inorganic hybrid perovskites greatly depend on their compositions. Here, we investigate the crystallization of methylammonium lead mixed halide (MAPbI_3–xBr_x) from microdroplets by adjusting the molar ratio of iodine to bromine in precursor solution, which helps to control the morphology, crystallinity, and physical properties of the perovskite materials. The composition of the precursor solutions has profound effects on the crystallization and perovskite morphology. It tends to form needle intermediate crystals of MAPbI_3−xBr_x·DMF from the precursor solution at low bromine concentration, while it tends to form flake or cubic perovskite of MAPbI_3−xBr_x at high bromine concentration. There is evident composition segregation of bromine when the perovskite and its intermediate grow freely from the solution at low temperature. At a high growing temperature of 100 °C, continuous perovskite films consisting of large crystal domains with sizes up to 100 μm are fabricated from the precursor solution.

中文翻译：

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从微滴中原位研究甲基铵卤化铅（MAPbI _{3– x} Br _x）钙钛矿的生长

有机-无机杂化钙钛矿的性质在很大程度上取决于它们的组成。在这里，我们通过调节前体溶液中碘与溴的摩尔比，研究了微滴中甲基铵铅混合卤化物（MAPbI _{3– x} Br _x）的结晶，这有助于控制钙钛矿材料的形态，结晶度和物理性能。 。前体溶液的组成对结晶和钙钛矿形态具有深远的影响。它倾向于在低溴浓度下从前体溶液中形成MAPbI _{3- x} Br _x ·DMF的针状中间晶体，而它倾向于形成MAPbI _{3- x的}片状或立方钙钛矿。高溴浓度下的Br _x。当钙钛矿及其中间体在低温下从溶液中自由生长时，溴的成分明显偏析。在100°C的高生长温度下，由前体溶液制备出连续的钙钛矿薄膜，该薄膜由尺寸最大为100μm的大晶畴组成。